Address Windows 64-bits warnings.

R=henrik.lundin@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/2203004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4803 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/audio_coding/neteq4/decoder_database.cc

@@ -28,7 +28,7 @@ DecoderDatabase::DecoderInfo::~DecoderInfo() {
 
 bool DecoderDatabase::Empty() const { return decoders_.empty(); }
 
-int DecoderDatabase::Size() const { return decoders_.size(); }
+int DecoderDatabase::Size() const { return static_cast<int>(decoders_.size()); }
 
 void DecoderDatabase::Reset() {
   decoders_.clear();